Variable resistance control

ABSTRACT

An electrical component of the variable resistance type having a base of electrically nonconductive material provided with an opening. A resistance element is disposed on one side of the base, and an apertured collector in registry with the opening is circumposed by the resistance element. A center terminal connected to the collector is provided with a recessed portion which is disposed in a cut out portion in the base. Such arrangement provides an uninterrupted track on the base for a driver constrained to rotate with a contactor engaging the resistance element and the collector.

June 17, 1975 United States Patent 191 Van Benthuysen et a].

644 677 HHH W888 /333 8333 3 H WHMW mm m mm m ..e Hu un n NU mmmm mnkfl d& d df d ua u BBVB 9088 5666 9990 236 584 2776 559 7278 .33 2233 [73] Assignee:

Filed:

Primary Examiner-A, T. Grimley [57] ABSTRACT An electrical component of the variable resistance [211 App]. No.: 732,137

Related US. Application Data Division of Ser. No. 620,186, March 2, No. 3,421,133.

I967, Pat.

type having a base of electrically nonconductive material provided with an opening. A resistance element is disposed on one side of the base, and an apertured collector in registry with the opening is circumposed by the resistance element. A center terminal connected to the collector is provided with a recessed 0024-O 000 9 I I Ms.., C 8 3 .3 8 3mm 4 5 7 2 m 3 m 4 3 mm U006 "36 HU3 HWMS mmm nu nnn mm mmc ,.r "3 w "U I I s UIF III 2100 555 III portion which is disposed in a cut out portion in the base. Such arrangement provides an uninterrupted track on the base for a driver constrained to rotate [56] References Cited UNITED STATES PATENTS with a contactor engaging the resistance element and the collector,

2,632,832 3/1953 Bush et 338/174 X 2,736,783 2/1956 Da|ly.....,..,...,...,.. 338/174 X 2,745,927 5/1956 Daily et al. 338/174 X 5 Claims, 4 Drawing Figures 1 VARIABLE RESISTANCE CONTROL This is a division of application Ser. No. 620,186 filed Mar. 2, 1967 which issued on Jan. 7, 1969, as US. Pat. No. 3,421,133. The present invention relates to electrical components and, more particularly, to a variable resistance control.

Low-cost electrical components, e.g., variable resistance controls, are generally employed in electrical apparatus such as television receivers, for trimming circuits periodically as the values of the components in the circuit change due to aging. These low-cost controls are usually pre-set by a television manufacturer after the set has been assembled and seldom need adjustment unless the set is being repaired by a serviceman. In some television receivers, the controls are located where only a serviceman can adjust them while other controls are adjustable externally of the receiver for controlling, e.g., contrast, vertical and horizontally synchronization, and the like. One of the features desired in a low-cost control is adequate bearing support for the driver. In certain prior art devices, adequate bearing support is obtained by providing a driver with an arcuate skirt having a bearing surface engaging the base of the control. To avoid interference between the center terminal and the arcuate skirt, the terminal is mounted against the rear surface of the base. The manufacturing cost of the control could be decreased slightly if the terminal could be mounted on the front surface of the control. It would, therefore, be desirable to provide a low-cost control having a driver with an arcuate skirt and having a center terminal mounted against the front surface of the base without having the terminal interfere with rotation of the driver.

Accordingly, it is an object of the present invention to provide a variable resistance control with a driver having an arcuate skirt engaging the front surface of an insulating base without having the driver interfere with a center terminal also mounted on the front surface of the base. Another object of the present invention is to provide a variable resistance control with an uninterrupted track on the front surface of a base between a collector and a resistance element mounted on the front surface of the base. An additional object of the present invention is to provide a variable resistance control with a stop integral with the center terminal for limiting angular rotation of a contactor constrained to relate with a driver. Further objects and advantages of the present invention will become apparent as the following description proceeds, and the features of novelty characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly, the invention comprises a variable resistance control having an arcuate resistance element and a collector fixedly secured to the front surface of an electrically insulated base. Terminals are connected to the ends of the resistance element and to the collector. The terminal connected to the collector is provided with a U-shaped portion disposed in a cut out portion in the base to provide an uninterrupted track on the front surface between the collector and the resistance element. A driver having an arcuate skirt rides in the uninterrupted track and a contactor constrained to rotate with the driver wipingly engages the collector and the resistance element intermediate the ends thereof. A stop is also provided on the center terminal for limiting angular rotation of the driver.

For a better understanding of the present invention, reference may be had to the accompanying drawings wherein the same reference numerals have been applied to like parts and wherein:

FlG. 1 is an isometric view of an electrical component having a pair of panel-mounting brackets secured to the base of the component for mounting the component to a panel;

FIG. 2 is a plan view of the electrical component shown in FIG. 1 without the brackets;

FIG. 3 is a side view of the electrical component shown in FIG. 2;

and FIG. 4 is a plan view of the mounting bracket shown in FIG. 1 for mounting the electrical component to a panel.

Referring now to FIGS. 1-3 of the drawings, there is illustrated an electrical component of the type employed in electrical apparatus such as television receives, generally indicated at 10, comprising three variable resistance controls 11 carried by a dielectric base 12 of suitable electrically nonconductive nonconductive material such as laminated plastic or alumina. Various types of variable resistance controls 11 or switches can be carried by the common base 12 by providing suitable mounting means such as a round opening 13 in the base. Means 14 defining a resistance path. i.e., a resistance element, is secured to the base 12 concentric to the opening 13 and comprises a carbon film 15 deposited on an arcuate strip 16 of insulating material such as laminated plastic or alumina fixedly secured to the base in a suitable manner such as with terminal lugs 17a. Thin metallized or cermet film can also be used. Conductive paths 18 in overlapping relationship with the ends of the carbon film connect the resistance element 14 to the end terminals 17. The carbon film can obviously be deposited directly onto the surface of the base 12. A flat ring collector l9 integral with a center terminal 20 fixedly secured to the base by a pair of terminal lugs 20a is concentric with the round opening 13 and the resistance element. A rotatable shift 21 having a reduced portion 21a is suitably secured in the round opening 13 by deforming the end portion 21b (see FIG. 3). A driver 22 molded to the shaft carries a contactor 23 having a pair of contacts 23a and 23b wipingly engaging the resistance element 14 and the collector 19 respectively as the shaft is rotated. More specifically, a peripheral skirt 22a integral with the driver 22 and con centric to the shaft 21 has a bearing surface 22b slidably engaging the annular track of the base 12 between the resistance element 14 and the collector 19. Recesses 22c provided in the skirt 22a receive radially extending arms 23c integral with the contactor 23 and constrain the contactor to rotate with the driver. To avoid interference between the peripheral skirt 22a and the center terminal 20, the base 12 is provided with a cut out portion 12b (see FIG. 1) and a U-shaped por tion 20b of the terminal 20 is disposed in the cut out portion providing an uninterrupted track 12a. One leg 20c of the U-shaped portion 20b of the terminal 20 extends above the base and functions as a stop member while stop means 22d carried by the driver is engageable with the stop member for limiting angular rotation of the driver. Preferably, the stop means 22d comprise spaced projections 22a and 22f on opposite sides of the contact 23a.

For the purpose of securing the electrical component 10 to a not-shown panel, a pair of flat mounting brack ets 24, preferably of metal or a suitable plastic are received in lower and upper notches and 26, one pair of notches being provided on opposite ends of the base 12. Obviously the upper notch could be part of the opening, hole, indentation on each side of the base or the like. Each of the mounting brackets comprises a bridging member 27 having a portion 270 (see FIG. 4) disposed in the notch 25 and preferably a side 27b abutting against the edge 12d of the base 12 (see FIG. I). A pair of arms 28 integral with the bridging member 27 span the distance between the notches 25 and 26 from opposite sides of the base 12. Gripping portions 29 connected to the ends of the arms 28 are in registry with the notch 26 and, since the distance between the gripping portions 29 is less than the thickness of the base, the gripping portions extend partially into the notch 26 engaging the base (see FIG. 4) and interlocking the mounting bracket to the base 12. It is, therefore, preferably that the mounting bracket be of a resilient metal, otherwise the arms will not spring back into the notch 26 after being spread apart by the base 12 during assembly of the mounting brackets to the base 12.

In a preferred form of the invention, a pair of legs 30 extending downwardly from the bridging member 27 and insertable into an opening, e.g., a rectangular slot, provided in the not-shown panel secures the mounting bracket 24 to the panel. Preferably, each of the legs is provided with an outwardly facing notch 31 having a front or outside width slightly greater than the thickness of the panel to facilitate mounting of the bracket 24 to the panel. The tapered end 300 of each of the legs and one Side 310 of the associated notch defines a hook. the hooks in each pair of legs being disposed in edgewise spaced relationship and substantially perpendicular to the base. The disposition of the legs enables the legs to be biased toward each other facilitating insertion of the legs into the slot provided in the panel. The other side 31!) of each of the notches 31 extends outwardly slightly farther than the one side 31a to limit insertion of the legs 30 into the slots provided in the panel. The slot in the panel preferably is of a length less than the distance between the notches 31 to assure that the mounting bracket 24 is rigidly supported in the panel. Preferably one or both sides 31a and 31b of each of the notches 3! are tapered to assure that the edges of the panel defining the slots always are wedged in the notches regardless ofa slight change in thickness of the panel. By making the width of the legs from the bridging member 27 to the notches 31 substantially equal, the desired resiliency in the legs is obtained. In a preferred form of the invention, the minimum width of the bridging member 27, i.e., the distance between the arms and the legs is substantially greater than the width of one of the legs to assure that the resiliency of the arms 28 is independent of the mounting means, that is, the legs. Substantially greater is at least 30 percent, preferably percent greater.

Preferably to assure that the mounting bracket 24 is rigidly secured to a base 12, a recess 32 having a width slightly less than the thickness of the base is provided in the bridging member. Upon assembly of the mounting bracket 27 to the base 12, the portion 120 of the base adjacent to the notch 25 is wedged into the recess 32 provided in the bridging member interlocking the bracket to the base (see FIG. 4). Longitudinal and rotational movement of the mounting bracket with respect to the base is eliminated since the portion 12d of the base adjactnt to the notch 25 is compressed in the recess 32 forming an interference fit between the base and the bridging member 27 of the mounting bracket while the portion of the base adjacent to the upper notch 26 is compressed by the gripping portions 29 connected to the arms.

What is claimed as new and desired to be secured by letters Patent of the United States is:

l. A variable resistance control comprising a base of electrically nonconductive material provided with an opening and having a front side and a rear side, means defining an arcuate resistance path on the front side of the base and equally spaced around the opening, collector means secured to the front side of the base and equally spaced from the first-mentioned means, said collector means being provided with a hole axially aligned with the opening, an annular track provided on the base between the resistance path and the collector means, said track being provided with a cut out portion, a center terminal connected to said collector means, a U-shaped terminal portion disposed in the cutout portion and having a pair of legs, one leg of the terminal portion being connected to the center terminal and the other leg being connected to the collector means, disposing of the terminal portion in the cut out portion providing an uninterrupted path on the track, a shaft passing through the hole and journaled in the opening, a driver connected to the shaft, a contactor adapted to wipe both of the means and constrained to rotate with the driver, a skirt integral with the driver slidable on the annular track, a stop member integral with the center terminal, and stop means carried by the driver engageable with the stop member for limiting angular rotation of the driver.

2. The control of claim 1, wherein the stop means comprises a pair of spaced projections integral with the driver, and a contact carried by the contactor is disposed between the spaced projections.

3. The control of claim I, wherein the stop means is spaced further from the rotational axis of the driver than the skirt.

4. A variable resistance control comprising a base of electrically nonconductive material provided with an opening and having a front side and rear side, means defining an arcuate resistance path on the front side of the base, said means positioned substantially concentric to the opening in the base, collector means disposed on the front side of the base and spaced from the first-mentioned means, said collector means being provided with a hole axially aligned with the opening, an annular track provided on the base between the firstmentioned means and the collector means, said track being provided with a cut out portion, a center terminal connected to said collector means, a terminal portion disposed in the cut out portion and having a pair of legs, one leg of the terminal portion being connected to the center terminal and the other leg being connected to the collector means, disposing of the terminal portion in the cut out portion providing an uninterrupted path on the track, a shaft passing through the hole and journaled in the opening, a driver connected to the shaft, a contactor adapted to wipe both of the means and constrained to rotate with the driver, an arcuate skirt integral with the driver slidable on the annular track, a stop member integral with the center terminal, and stop means carried by the driver engageable with the stop member for limiting angular rotation of the 3,890,590 6 driver, and terminals connected to the first-mentioned shaped and the bight thereof is disposed in the cut out means. portion in the base, and means securing the terminal to 5. The control of claim 4, wherein the cut out portion the base. extends through the base, the terminal portion is U- 

1. A variable resistance control comprising a base of electrically nonconductive material provided with an opening and having a front side and a rear side, means defining an arcuate resistance path on the front side of the base and equally spaced around the opening, collector means secured to the front side of the base and equally spaced from the first-mentioned means, said collector means being provided with a hole axially aligned with the opening, an annular track provided on the base between the resistance path and the collector means, said track being provided with a cut out portion, a center terminal connected to said collector means, a U-shaped terminal portion disposed in the cutout portion and having a pair of legs, one leg of the terminal portion being connected to the center terminal and the other leg being connected to the collector means, disposing of the terminal portion in the cut out portion providing an uninterrupted path on the track, a shaft passing through the hole and journaled in the opening, a driver connected to the shaft, a contactor adapted to wipe both of the means and constrained to rotate with the driver, a skirt integral with the driver slidable on the annular track, a stop member integral with the center terminal, and stop means carried by the driver engageable with the stop member for limiting angular rotation of the driver.
 2. The control of claim 1, wherein the stop means comprises a pair of spaced projections integral with the driver, and a contact carried by the contactor is disposed between the spaced projections.
 3. The control of claim 1, wherein the stop means is spaced further from the rotational axis of the driver than the skirt.
 4. A variable resistance control comprising a base of electrically nonconductive material provided with an opening and having a front side and rear side, means defining an arcuate resistance path on the front side of the base, said means positioned substantially concentric to the opening in the base, collector means disposed on the front side of the base and spaced from the first-mentioned means, said collector means being provided with a hole axially aligned with the opening, an annular track provided on the base between the first-mentioned means and the collector means, said track being provided with a cut out portion, a center terminal connected to said collector means, a terminal portion disposed in the cut out portion and having a pair of legs, one leg of the terminal portion being connected to the center terminal and the other leg being connected to the collector means, disposing of the terminal portion in the cut out portion providing an uninterrupted path on the track, a shaft passing through the hole and journaled in the opening, a driver connected to the shaft, a contactor adapted to wipe both of the means and constrained to rotate with the driver, an arcuate skirt integral with the driver slidable on the annular track, a stop member integral with the center terminal, and stop means carried by the driver engageable with the stop member for limiting angular rotation of the driver, and terminals connected to the first-mentioned means.
 5. The control of claim 4, wherein the cut out portion extends through the base, the terminal portion is U-shaped and the bight thereof is disposed in the cut out portion in the base, and means securing the terminal to the base. 